Women are often irritated by their bras because, little do they know, they are wearing the wrong size bra. This is typically due to women thinking they know what cup size and bust size they are but really not being quite sure. Here's how to correctly measure the bust.
Place the tape measure around your body, just under your breasts. Keep your arms down at your side. Make sure the tape measure remains horizontal.
Check the measurement. The number on the tape measure is your true bust, but for fitting bras you need to round to the nearest even number. So if your bust is 33 1/2 inches, round up to 34 inches.
Place the tape measure around your back and across your nipples. It should wrap around loosely, not as tight as possible. Take note of the measurement.
Figure out your cup size. Compare the two measurements. If there is less than one inch difference, you're an AA cup, one inch an A, two inches a B, three inches a C, four inches a D, and so on. That's it! You have your bust and cup size!